Evaluation of the risk of infection through exposure to aerosols and spatters in dentistry.

BACKGROUND: Many dental procedures produce extensive aerosols and splatters that are routinely contaminated with microorganisms. METHODS: Air containing blood-bearing aerosols and surfaces contaminated by sedimenting blood particulate was sampled in 5 different dental cubicles. To assess contamination by blood particulate, the concentration of hemoglobin (Hb) in the air and on the sedimentation surfaces was determined. RESULTS: The mean concentration of Hb in the air aspirated in the 5 cubicles was 0.14 +/- 0.23 microg/m(3), corresponding to a blood volume of 8.7 x 10(-4) microL/m(3). Similarly, the mean concentration of blood particulate sedimented on surfaces was calculated and found to be 1.56 microL/m(2). In 80% of the cubicles monitored, 100% positivity to the Hb determination test was recorded in all of the surface samples. CONCLUSIONS: The results obtained revealed contamination of both air and surfaces by blood particulate. Moreover, with the exception of those obtained in 1 cubicle, all of the samples of sedimenting particulate analyzed were positive for the presence of Hb.

Using a bioaerosol personal sampler in combination with real-time PCR analysis for rapid detection of airborne viruses.

We have recently developed a new personal sampler and demonstrated its feasibility for detection of viable airborne microorganisms including bacteria, fungi and viruses. To accelerate the time-consuming analytical procedure involving 2-5 days of biological testing, we employed a real-time PCR protocol in conjunction with the personal sampler for collection of airborne viruses. The advantage of this approach is that if the presence of a particular pathogen in the air is detected by the PCR, the remaining collecting liquid can be further analysed by more time-consuming biological methods to estimate the number of airborne infectious/live microorganisms. As sampling of bioaerosols in natural environments is likely to be associated with substantial contamination by a range of microorganisms commonly existing in an ambient air, an investigation of the specificity of detection by targeted PCR analysis is required. Here we present the results of the study on the detection of Influenza virus in the ambient air contaminated with high concentrations of bacteria and fungi using real-time PCR protocol. The combined sampling PCR detection method was found to be fully feasible for the rapid ( approximately 2.5 h) and highly specific (no cross-reactivity) identification of the labile airborne virus in the air containing elevated concentrations of other microorganisms.

Room size is the major determinant for tuberculin conversion in health care workers exposed to a multidrug-resistant tuberculosis patient.

OBJECTIVE: Transmission of Mycobacterium tuberculosis (MTB) to health care workers (HCWs) still represents a public health concern. A total of 71 obstetric workers underwent contact tracing after recent workplace exposure to a highly infectious multidrug-resistant tuberculosis patient [i.e., index case (IC)]. Aim of the study was to identify the main exposure predictors for the risk of conversion through evaluation of tuberculin screening results. METHODS: HCWs were investigated by a questionnaire (community, occupational, IC exposure risk factors) and tuberculin skin test screening. RESULTS: Conversion was detected in 5 (8%) of the 63 exposed workers and was not associated with either community or previous work-related risk factors. According to risk assessment, tuberculin conversion was related to neither amount time of exposure, workshifts, nor number of contacts. Conversely, an exposure to the IC in different hospital rooms was found significantly different among converters compared to non-converters (chi (2), P = 0.004). In particular, conversion was associated with exposure in two (obstetric emergency room, ambulatory discharge) out of the nine contact environments. Tuberculin conversion rates were associated with the room cubations of the exposure environments (chi (2) for trend, P < 0.01) and with worker age. In a logistic regression model adjusted for age, the lower room cubation was found the strongest predictor for tuberculin conversion (OR = 2.46, P = 0.02). CONCLUSION: The study shows that the factors affecting airborne mycobacterial dose (patient infectiousness, low sized confined rooms) were the major determinants for MTB transmission after a brief exposure to a highly infectious TB case.

Factors associated with nosocomial SARS-CoV transmission among healthcare workers in Hanoi, Vietnam, 2003.

BACKGROUND: In March of 2003, an outbreak of Severe Acute Respiratory Syndrome (SARS) occurred in Northern Vietnam. This outbreak began when a traveler arriving from Hong Kong sought medical care at a small hospital (Hospital A) in Hanoi, initiating a serious and substantial transmission event within the hospital, and subsequent limited spread within the community. METHODS: We surveyed Hospital A personnel for exposure to the index patient and for symptoms of disease during the outbreak. Additionally, serum specimens were collected and assayed for antibody to SARS-associated coronavirus (SARS-CoV) antibody and job-specific attack rates were calculated. A nested case-control analysis was performed to assess risk factors for acquiring SARS-CoV infection. RESULTS: One hundred and fifty-three of 193 (79.3%) clinical and non-clinical staff consented to participate. Excluding job categories with < 3 workers, the highest SARS attack rates occurred among nurses who worked in the outpatient and inpatient general wards (57.1, 47.4%, respectively). Nurses assigned to the operating room/intensive care unit, experienced the lowest attack rates (7.1%) among all clinical staff. Serologic evidence of SARS-CoV infection was detected in 4 individuals, including 2 non-clinical workers, who had not previously been identified as SARS cases; none reported having had fever or cough. Entering the index patient's room and having seen (viewed) the patient were the behaviors associated with highest risk for infection by univariate analysis (odds ratios 20.0, 14.0; 95% confidence intervals 4.1-97.1, 3.6-55.3, respectively). CONCLUSION: This study highlights job categories and activities associated with increased risk for SARS-CoV infection and demonstrates that a broad diversity of hospital workers may be vulnerable during an outbreak. These findings may help guide recommendations for the protection of vulnerable occupational groups and may have implications for other respiratory infections such as influenza.

Actualización del coste de las inoculaciones accidentales en el personal sanitario hospitalario / Update of the cost of needlestick injuries in hospital healthcare personnel

Objetivos: Actualizar el coste medio a que asciende cada seguimiento de la hepatitis B y C, así como la infección por el virus de la inmunodeficiencia humana (VIH), en el personal sanitario que ha experimentado una inoculación accidental, desagregar el coste según el estado serológico de la fuente e identificar los apartados que influyen en mayor grado en la cuantía de este resultado. Métodos: Se realizó una descripción de los costes. El programa post exposición se modelizó en un árbol de decisión que combinaba las probabilidades (porcentaje de cada tipo de fuente en función de su positividad a los 3 virus e inmunización del accidentado frente a la hepatitis B) y los costes monetarios(en euros del año 2002) relacionados con los gastos de personal, laboratorio, farmacia (incluida la profilaxis post exposición frente al VIH), energéticos, de limpieza, teléfono, material médico y de oficina, amortización y pérdidas productivas. Resultados: El coste medio de cada inoculación fue de 388 euros, con un rango de 1.502 (fuente positiva a la hepatitis C y el VIH) a 172 euros (fuente negativa a los 3 virus). Si la fuente era la hepatitis B positiva, el coste medio fue de 666 euros cuando el accidentado no estaba inmunizado, y de 467 si efectivamente lo estaba. La mayor parte del coste residió en las pruebas serológicas y la administración de profilaxis post exposición. Conclusiones: El alto coste indica una evaluación adecuada del riesgo con el fin de evitar unos seguimientos innecesarios. El modelo permite conocer el coste de cada episodio potencialmente evitable y puede aplicarse en cualquier hospital, con el objetivo de evaluar económicamente los nuevos dispositivos preventivos

Objectives: To update the mean cost of each hepatitis B, hepatitis C and HIV follow-up in health personnel accidentally exposed to blood and body fluids, to stratify the cost depending on the serological status of the source, and to identify the items that account for the main part of the cost. Methods: A cost analysis was carried out. The post exposure program was modeled on a decision tree combining probabilities(percentage of each type of source depending on positivity for the three viruses and immunization status of the health worker against hepatitis B) and monetary costs (eurosin 2002). Costs included salaries, laboratory, pharmacy (including post exposure prophylaxis), water, gas and electricity, cleaning, telephone, medical and office equipment, amortization and lost productivity. Results: The mean cost was 388 euros, ranging from 1,502 euros (source positive for hepatitis C and HIV) to 172 euros(source negative for the three viruses). If the source was hepatitis B positive, the mean cost was 666 euros when the injured worker was not immunized and was 467 euros if the worker was immunized. Serologic tests and post exposure prophylaxis accounted for the main part of the cost. Conclusions: The high cost suggests the need for appropriate risk evaluation to avoid unnecessary follow-ups. The model used allows the cost of each potentially avoidable episode to be determined and could be used in any hospital to performan economic evaluation of new preventive devices

[Sero-epidemiological characteristics of antibody to SARS-associated coronavirus in Gansu Province].

OBJECTIVE: To study the levels of SARS-associated coronavirus IgG antibody of SARS patients, people who closely contacted SARS patients and normal subjects in Gansu province. METHODS: The levels of SARS-associated coronavirus IgG antibody were measured by ELISA. The material included acute and (or) recovery period sera of 9 SARS patients, sera from 1,109 doctors and nurses closely contacted with SARS patients, laboratory workers, personnel for disease control and prevention, persons who contacted SARS patients, and sera from 978 normal subjects. RESULTS: SARS coronavirus IgG antibody was detected positive in 6 of the 9 patients, it was still positive in the sera twelve months after recovery; 1 of the closely contacted persons and 3 normal subjects were found positive. CONCLUSION: The positive rate of SARS coronavirus IgG antibody of patients was consistent with the clinical diagnosis. The low positive rate of the persons who closely contacted SARS patients and normal subjects suggests that SARS probably had no subclinical infection.

Occupationally acquired human immunodeficiency virus (HIV) infection: national case surveillance data during 20 years of the HIV epidemic in the United States.

OBJECTIVE: To characterize occupationally acquired human immunodeficiency virus (HIV) infection detected through case surveillance efforts in the United States. DESIGN: National surveillance systems, based on voluntary case reporting. SETTING: Healthcare or laboratory (clinical or research) settings. PATIENTS: Healthcare workers, defined as individuals employed in healthcare or laboratory settings (including students and trainees), who are infected with HIV. METHODS: Review of data reported through December 2001 in the HIV/AIDS Reporting System and the National Surveillance for Occupationally Acquired HIV Infection. RESULTS: Of 57 healthcare workers with documented occupationally acquired HIV infection, most (86%) were exposed to blood, and most (88%) had percutaneous injuries. The circumstances varied among 51 percutaneous injuries, with the largest proportion (41%) occurring after a procedure, 35% occurring during a procedure, and 20% occurring during disposal of sharp objects. Unexpected circumstances difficult to anticipate during or after procedures accounted for 20% of all injuries. Of 55 known source patients, most (69%) had acquired immunodeficiency syndrome (AIDS) at the time of occupational exposure, but some (11%) had asymptomatic HIV infection. Eight (14%) of the healthcare workers were infected despite receiving postexposure prophylaxis (PEP). CONCLUSIONS: Prevention strategies for occupationally acquired HIV infection should continue to emphasize avoiding blood exposures. Healthcare workers should be educated about both the benefits and the limitations of PEP, which does not always prevent HIV infection following an exposure. Technologic advances (eg, safety-engineered devices) may further enhance safety in the healthcare workplace.

Factors influencing human immunodeficiency virus postexposure prophylaxis requests after low-risk occupational exposure.

OBJECTIVES: To determine the factors influencing human immunodeficiency virus postexposure prophylaxis (PEP) requests after "low-risk" occupational exposure. METHODS: We analyzed data from low-risk occupational exposures reported between January 1999 and May 2000. RESULTS: A total of 318 low-risk occupational exposures were reported. No worker demographic variable, exposure method, or exposure type was associated with increased PEP requests. Exposed workers were more likely to request PEP if the source patient was unknown or 18 to 49 years old. No other source patient demographic variable was associated with increased PEP requests. CONCLUSIONS: We found that workers who experienced a low-risk occupational exposure were more likely to request PEP when the source patient was unknown or 18 to 49 years of age. No other factors were associated with increased PEP requests.

Risk of exposure to bloodborne infection for Italian healthcare workers, by job category and work area. Studio Italiano Rischio Occupazionale da HIV Group.

OBJECTIVE: To analyze the rate of occupational exposure to blood and body fluids from all sources and specifically from human immunodeficiency virus (HIV)-infected sources among hospital workers, by job category and work area. DESIGN: Multicenter prospective study. Occupational exposure data (numerator) and full-time equivalents ([FTEs] denominator) were collected over a 5-year period (1994-1998) and analyzed. SETTING: 18 Italian urban acute-care hospitals with infectious disease units. RESULTS: A total of 10,988 percutaneous and 3,361 mucocutaneous exposures were reported. The highest rate of percutaneous exposure per 100 FTEs was observed among general surgery (11%) and general medicine (10.6%) nurses, the lowest among infectious diseases (1.1%) and laboratory (1%) physicians. The highest rates of mucocutaneous exposure were observed among midwives (5.3%) and dialysis nurses (4.7%), the lowest among pathologists (0%). Inadequate sharps disposal and the prevalence of sharps in the working unit influence the risk to housekeepers. The highest combined HIV exposure rates were observed among nurses (7.8%) and physicians (1.9%) working in infectious disease units. The highest rates of high-risk percutaneous exposures per 100 FTE were again observed in nurses regardless of work area, but this risk was higher in medical areas than in surgery (odds ratio, 2.1; 95% confidence interval, 1.9-2.5; P<.0001). CONCLUSION: Exposure risk is related to job tasks, as well as to the type and complexity of care provided in different areas, whereas HIV exposure risk mainly relates to the prevalence of HIV-infected patients in a specific area. The number of accident-prone procedures, especially those involving the use of hollow-bore needles, performed by job category influence the rate of exposure with high risk of infection. Job- and area-specific exposure rates permit monitoring of the effectiveness of targeted interventions and control measures over time.

Prospective evaluation of the utility of molecular techniques for diagnosing nosocomial transmission of multidrug-resistant tuberculosis.

OBJECTIVE: To compare molecular techniques with conventional diagnostic methods for evaluating nosocomial transmission of multidrug-resistant tuberculosis (MDR-TB). DESIGN: We conducted a 12-week postexposure inception cohort study of health-care personnel who had been exposed to a patient with MDR-TB. MATERIAL AND METHODS: In addition to baseline and follow-up tuberculin skin tests and chest roentgenography, weekly pulmonary specimens were evaluated by (1) auramine-rhodamine fluorescent staining, (2) culture for mycobacteria, and (3) polymerase chain reaction (PCR) to amplify IS6110, a nucleic acid insertion sequence unique to the Mycobactrium tuberculosis complex. RESULTS: The index patient's isolate of M. tuberculosis showed a mutation in codon 531 of the RNA polymerase beta subunit (rpoB) gene of M. tuberculosis, which is associated with rifampin resistance and considered a marker for this MDR-TB strain. All pulmonary and gastric specimens from study participants had negative auramine stains and cultures for mycobacteria, One person, however, had separate specimens with repeatedly positive PCR results for IS6110 sequences, but the specimens contained a wild-type M. tuberculosis rpoB codon 531 dissimilar from the index patient's strain. CONCLUSION: Although both molecular and conventional testing showed that no exposed person was infected with the MDR-TB strain, molecular test results were available sooner and seemed more sensitive for detecting M. tuberculosis in one exposed person, presumably in a preinfection or "colonized" stage. Molecular methods provided information that helped distinguish this person's M. tuberculosis strain from the index patient's MDR-TB strain. Additional prospective studies should assess the value of these molecular techniques in similar clinical settings.